Greg Huffman

A touchy subject: advancing the modulated visual pathways account of altered vision near the hand

Abstract A growing body of evidence demonstrates that human vision operates differently in the space near and on the hands; for example, early findings in this literature reported that rapid onsets are detected faster near the hands, and that objects are searched more thoroughly. These and many other effects were attributed to enhanced attention via the recruitment of bimodal visual-tactile neurons representing the hand and near-hand space. However, recent research supports an alternative account: stimuli near the hands are preferentially processed by the action-oriented magnocellular visual pathway at the expense of processing in the parvocellular pathway. This Modulated Visual Pathways (MVP) account of altered vision near the hands describes a hand position-dependent trade-off between the two main retinal-cortical visual pathways between the eye and brain. The MVP account explains past findings and makes new predictions regarding near-hand vision supported by new research.

Acting and anticipating: impact of outcome-compatible distractor depends on response selection efficiency

Action selection is thought to involve selection of the actions sensory outcomes. This notion is supported when encountering a distractor that resembles a learned response-outcome biases response selection. Some evidence, however, suggests that a larger contribution of stimulus-based response selection leaves little role for outcome-based selection, especially in forced-choice tasks with easily identifiable target stimuli. In the present study, we asked whether the contribution of outcome-based selection depends on the ease and efficiency of stimulus-based selection. If so, then efficient stimulus-based response selection should reduce the impact of an irrelevant distractor that resemble a response-outcome. We manipulated efficiency of stimulus-based selection by varying the spatial relationship between stimulus and response (Experiment 1) and by varying stimulus discriminability (Experiments 2). We hypothesized that with efficient stimulus-based selection, outcome-based processes will play a weaker role in response selection, and performance will be less susceptible to outcome-compatible or -incompatible distractors. By contrast, when stimulus-based selection is relatively inefficient, outcome-based processes will play a stronger role in response selection, and performance should be more susceptible to outcome-compatible or -incompatible distractors. Confirming our predictions, our results showed stronger impact of the distractors when stimulus-based response selection was relatively inefficient. Finally, results of a control experiment (Experiment 3) suggested that learning the consistent response-outcome mapping is necessary for obtaining the effect of these distractors. We conclude that outcome-based processes do contribute to response selection in forced-choice tasks, and that this contribution varies with the efficiency of stimulus-based response selection. (PsycINFO Database Record

Hand position influences perceptual grouping

Abstract Over the past decade, evidence has accumulated that performance in attention, perception, and memory-related tasks are influenced by the distance between the hands and the stimuli (i.e., placing the observer’s hands near or far from the stimuli). To account for existing findings, it has recently been proposed that processing of stimuli near the hands is dominated by the magnocellular visual pathway. The present study tests an implication of this hypothesis, whether perceptual grouping is reduced in hands-proximal space. Consistent with previous work on the object-based capture of attention, a benefit for the visual object in the hands-distal condition was observed in the present study. Interestingly, the object-based benefit did not emerge in the hands-proximal condition, suggesting perceptual grouping is impaired near the hands. This change in perceptual grouping processes provides further support for the hypothesis that visual processing near the hands is subject to increased magnocellular processing.

Intervening response events between identification targets do not always turn repetition benefits into repetition costs

When there is a relatively long interval between two successive stimuli that must be detected or localized, there are robust processing costs when the stimuli appear at the same location. However, when two successive visual stimuli that must be identified appear at the same location, there are robust same location costs only when the two stimuli differ in their responses; otherwise same location benefits are observed. Two separate frameworks that inhibited attentional orienting and episodic integration, respectively, have been proposed to account for these patterns. Recent findings hint at a possible reconciliation between these frameworks—requiring a response to an event in between two successive visual stimuli may unmask same stimulus and same location costs that are otherwise obscured by episodic integration benefits in identification tasks. We tested this hybrid account by integrating an intervening response event with an identification task that would otherwise generate the boundary between same location benefits and costs. Our results showed that the intervening event did not alter the boundary between location repetition benefits and costs nor did it reliably or unambiguously reverse the common stimulus-response repetition benefit. The findings delimit the usefulness of an intervening event for disrupting episodic integration, suggesting that effects from intervening response events are tenuous. The divide between attention and feature integration accounts is delineated in the context of methodological and empirical considerations.

Response-mediated spatial priming despite perfectly valid target location cues and intervening response events

ABSTRACT Attentional effects are often inferred from keypress reaction time (RT) studies when two sequentially presented stimuli, appearing at the same location, generate costs or benefits. The universality of these attentional attributions is challenged by data from perceptual discrimination tasks, which reveal that location repetition benefits and costs depend on whether a prior response repeats or switches, respectively. According to dual-stage accounts, these post-attentional effects may be abolished by making responses in between two target stimuli or by increasing target location certainty, leaving only attentional effects. Here, we test these accounts by requiring responses to stimuli in between targets and by increasing target location certainty with 100% valid location cues. Contrary to expectations, there was no discernible effect of cueing on any repetition effects, although the intervening response diminished stimulus-response repetition effects while subtly reducing location-response repetition effects. Despite this, there was little unambiguous evidence of attentional effects independent of responding. Taken together, the results further highlight the robustness of location-response repetition effects in perceptual discrimination tasks, which challenge whether there are enduring attentional effects in this paradigm.

The action effect: Support for the biased competition hypothesis

The action effect refers to the finding that faster response times are found when a previously responded to stimulus contains a target item than when it serves as a distracting item in a visual search. The action effect has proven robust to a number of perceptual and attentional manipulations, but the mechanisms underlying it remain unclear. In the current study, we present two experiments investigating a possible underlying mechanism of the action effect; that responding to a stimulus increases its attentional weight causing the system to prioritize it in the visual search. In Experiment 1, we presented the search stimulus in isolation and found no evidence of an action effect. Thus, when there was no requirement for prioritization, there was no action effect. In Experiment 2, we tested whether stimulus-based priming (rather than the action) can account for the observed validity effects. We found no evidence of a priming effect when there were never any actions. These findings are consistent with the biased competition hypothesis and provide a framework for explaining the action effect while also ruling out other potential explanations such as event file updating.

Salience drives non-spatial feature repetition effects in cueing tasks

In an exogenous cueing task repeating a non-spatial feature can benefit performance if the feature is task-relevant to a discrimination response. Previous studies reporting this effect have used complex displays. In the current study, we look at the generalizability of this effect, by extending it to a simple exogenous cueing paradigm in which the cue and target displays each consist of single-object onsets. We also investigate the influence of task-relevant and irrelevant features independently within the same experiment. Consistent with previous studies, we find non-spatial feature repetition benefits in all three experiments. Importantly, and unlike previous studies, we find that the most salient, rather than the task-relevant, feature drives the non-spatial feature repetition benefit. Furthermore, in addition to the previously observed non-spatial feature repetition benefits, we also found a spatially specific feature repetition benefit. We argue that these new findings are consistent with habituation accounts of attentional cueing effects.

I before U: Temporal order judgements reveal bias for self-owned objects:

A multitude of studies demonstrate that self-relevant stimuli influence attention. Self-owned objects are a special class of self-relevant stimuli. If a self-owned object can indeed be characterised as a self-relevant stimulus then, consistent with theoretical predictions, a behavioural effect of ownership on attention should be present. To test this prediction, a task was selected that is known to be particularly sensitive measure of the prioritisation of visual information: the temporal order judgement. Participants completed temporal order judgements with pictures of “own” and “experimenter” owned objects (mugs) presented on either side of a central fixation cross. There was a variable onset delay between each picture, ranging between 0 ms and 105 ms, and participants were asked to indicate which mug appeared first. The results indicated a reliable change in the point of subjective simultaneity (PSS) in favour of their own mug. Such a change in the PSS was not observed for two groups of participants who were exposed to a mug but did not keep the mug. A further experiment indicated that the source of the bias in PSS was more consistent with a criterion shift or top-down attentional prioritisation rather than a perceptual bias. These findings suggest that ownership, beyond mere-touch, mere-choice, or familiarity, leads to prioritised processing and responses, but the mechanism underlying the effect is not likely to be perceptual in nature.

Dissociating Orienting Biases From Integration Effects With Eye Movements

Despite decades of research, the conditions under which shifts of attention to prior target locations are facilitated or inhibited remain unknown. This ambiguity is a product of the popular feature discrimination task, in which attentional bias is commonly inferred from the efficiency by which a stimulus feature is discriminated after its location has been repeated or changed. Problematically, these tasks lead to integration effects; effects of target-location repetition appear to depend entirely on whether the target feature or response also repeats, allowing for several possible inferences about orienting bias. To parcel out integration effects and orienting biases, we designed the present experiments to require localized eye movements and manual discrimination responses to serially presented targets with randomly repeating locations. Eye movements revealed consistent biases away from prior target locations. Manual discrimination responses revealed integration effects. These data collectively revealed inhibited reorienting and integration effects, which resolve the ambiguity and reconcile episodic integration and attentional orienting accounts.

Response preparation, response selection difficulty, and response-outcome learning

Voluntary action control is accomplished through anticipating that action’s perceptual outcomes. Some evidence suggests that this is only true when responses are intention-based rather than stimulus-based and that this difference is evidence of different response modes. More recently, however, it has been shown that response-outcome retrieval effects can occur with stimulus-based responses, and that the retrieval depended on response selection efficiency as decreasing the response selection efficiency increased response-outcome retrieval (Gozli et al., J Exp Psychol: Hum Percept Perform, 2016). We look to extend this finding by manipulating response selection difficulty within (Experiment 1) or between blocks (Experiment 2) and response preparation time (Experiment 1) within an experiment. Individuals completed a task in which they responded to onsets using the spatially corresponding finger. The onset was preceded by precues narrowing down the response possibilities from four to two. The response possibilities were either on the same hand or different hands, such that response selection was easy or hard. We also varied the amount of time between the cues and the targets to manipulate response preparation time. The results indicated that trial-by-trial manipulations of response selection difficulty did not influence response-outcome retrieval, but that the between groups manipulation of response preparation time did. With less time response preparation time, larger response-outcome compatibility effects were found. This study presents further evidence that response selection efficiency can influence response-outcome retrieval and that this difference can be accounted for in terms of how prepared the responses are at the time of target presentation.